By TIMOTHY A. HACSI

In this respect, she has had quite a bit of company over the decades. In 1996, Washington hired a former three-star Army general, Julius W. Becton Jr., to take over its low-performing schools; he left, exhausted, after less than two years. For most of the last decade, the Los Angeles Unified School District was run by non-educators: a former governor of Colorado, Roy Romer, and then a retired vice admiral, David L. Brewer III. They got mixed reviews. Raj Manhas, who had a background in banking and utilities, ran Seattle’s schools from 2003 to 2007, balancing the budget but facing fierce opposition over his plans to close schools.

Mayor Michael R. Bloomberg, who had hired Ms. Black without public discussion, quickly replaced her with a deputy mayor steeped in education policy. But the real issue is not the superintendent’s or chancellor’s background, but the excessive emphasis that politicians, educators and parents place on the notion of leadership rather than on empirical evidence about what improves education.

Even as the specific fixes advocated for schools have changed, the role of school-district leaders has gotten greater attention — and the selection process has become more political.

It doesn’t always take actual success to be lauded and promoted, nor does an education background guarantee anything. Roderick R. Paigebecame superintendent of Houston schools in 1994 and in 2001 parlayed his “Houston miracle” to become President George W. Bush’s secretary of education, and the point man for the No Child Left Behind law. That Houston’s test-score increases and low dropout rates were mirages did not impede Mr. Paige’s ascent or the emphasis on testing as a magic bullet.

Perhaps the best-known school leader today is Michelle A. Rhee, who was schools chancellor in Washington from 2007 to 2010. She aggressively took on the teachers’ union, but made more headlines than lasting reforms.

Of course, judging success is difficult. It is not clear what a superintendent would have to do to be universally seen as successful by teachers, parents, politicians, businessmen and taxpayers. One person’s savior is another’s villain, just as in politics. And unlike in politics, superintendents often have second lives; look no further than two of Ms. Black’s predecessors, Ramon C. Cortines, now the superintendent in Los Angeles, and Rudolph F. Crew, who became superintendent in Miami.

The record shows, however, that serial superintendents tend to do worse — at least in public perception — in their later jobs, which would seem to argue against the importance of experience in the field of education.

Ms. Rhee’s predecessor in Washington, Clifford B. Janey, had run the schools in Rochester, where he seems to have had a positive impact on test scores and the achievement gap. From Washington he went to Newark, where after two years he was shown the door.

Paul G. Vallas’s tenure as the head of Chicago’s schools, from 1995 to 2001, was generally seen as a success. His later stint in Philadelphia was less triumphant, relying as it did on privatizing school management, an idea with ideological appeal but little supporting evidence. Now he runs the schools in New Orleans, a herculean task.

Americans’ forward-looking disposition has many advantages, but one downside is that we tend to avoid problems as they develop and then either rise to the occasion (think World War II), or take half-hearted steps before moving on (think of New Orleans). School reform requires long-term efforts, but instead we look for a George Washington to fix our schools through intelligence, strength of will and, more recently, going after the right enemies (namely unions).

The singular attention on school-district leaders is a consequence of developments over the last three decades or so. In 1978, Proposition 13, which capped property taxes in California, convinced politicians across the country that tax increases amounted to political suicide, thereby making it harder to increase school financing. In 1983, “A Nation at Risk,” a government report that was more publicized than read, declared our public schools to be failing. Since then education reform has been driven by a fear of international economic competition but also constrained financially; superintendents come and go, while the challenges mount.

Cathie Black lasted only three months instead of the more typical three years, but her failure seems more one of public relations than of educational leadership. The problem is all the time we spend talking about how the last leader failed, how the current leader is struggling, how the next leader must succeed.

Until the headlines and our attention focus on what the research shows can directly improve school performance — additional money, used wisely; longer school days; better-paid and better-prepared teachers; year-round schooling — instead of the latest savior/soon-to-be-failure, we, like Ms. Black and Mr. Bloomberg, are missing the point.

Timothy A. Hacsi, an assistant professor of history at the University of Massachusetts, Boston, is the author of “Children as Pawns: The Politics of Educational Reform.”